If you have already created a version, you will be able to preview it before putting it online.
This feature will enable you to check beforehand how the new version will look to the end user, or test something directly as it was deployed, before actually publishing content to your users.
In order to do so, you need to go to the publishing tab, click on the three dots on the right of the version you want to preview, and then click on "Preview".
Once you have done that, the browser where you did this interaction will go in preview mode.
By clicking the blue link, you will be redirected to your target application to check the version you are previewing.
Keep in mind that the preview mode is related to the current browser you are using and only you will see this, meaning that if you open another Browser instance, you will see the live version (if any was published). The same goes for any other user.
This enables you to also check multiple versions, with different browser windows, and might be very useful if you want to check different Journeys for one specific process.
If you want to exit preview mode, simply click the three dots of the version and then click on "Stop preview".
Keep in mind that only one preview can be available at a time, on all sites, per browser.